Phosphate adsorbent with rodlike structure as well as preparation method and application of phosphate adsorbent

Abstract

The invention discloses a phosphate adsorbent with a rod-like structure as well as a preparation method and application thereof, and relates to the technical field of sewage treatment materials. According to the preparation method of the phosphate adsorbent, the molar ratio of magnesium nitrate to sodium carbonate to sodium hydroxide in the reaction process is specifically controlled, so that the generated reaction product is a mixture of magnesium carbonate and magnesium hydroxide in a specific ratio, and the magnesium carbonate and the magnesium hydroxide can be calcined according to different decomposition temperatures of the magnesium carbonate and the magnesium hydroxide during calcination. Through targeted adjustment of a calcination process, the calcination process and a reaction product can achieve a synergistic effect, and the number, distribution and pore size of pores in the rodlike porous magnesium oxide are remarkably improved, so that the specific surface area and oxygen vacancy of the obtained rodlike porous magnesium oxide are remarkably improved, and then the adsorption capacity and efficiency of phosphate are remarkably improved; the adsorbent is suitable for large-scale application as a phosphate adsorbent; the preparation method is simple in step, controllable in process, stable in product performance and suitable for large-scale production of the phosphate adsorbent with the rod-like structure.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment materials, and in particular to a phosphate adsorbent material, in particular to a rod-shaped phosphate adsorbent and a preparation method and application thereof. Background Art

[0002] Phosphate is one of the important nutrients in water bodies and is widely present in natural water bodies, soil and organisms. In natural ecosystems, an appropriate amount of phosphate is of great significance for maintaining ecological balance and biological growth and development. However, with the rapid development of industry and the continuous growth of population, a large amount of phosphorus-containing wastewater is discharged into the environment, resulting in a sharp increase in the phosphate content in water bodies, causing serious environmental problems.

[0003] In water bodies, excessive phosphates can cause eutrophication. Eutrophication refers to the phenomenon that, under the influence of human activities, nutrients such as nitrogen and phosphorus required by organisms enter slow-flowing water bodies such as lakes, estuaries, and bays in large quantities, causing algae and other plankton to reproduce rapidly, the amount of dissolved oxygen in the water to decrease, the water quality to deteriorate, and fish and other organisms to die in large numbers. The main characteristics of eutrophic water bodies are: the large-scale reproduction of phytoplankton reduces the transparency of the water body and makes it difficult for sunlight to penetrate the water layer, thus affecting the normal function of the aquatic ecosystem. The large-scale reproduction of algae will also consume the dissolved oxygen in the water, causing hypoxia in the water body and suffocating the aquatic organisms to death. In addition, the toxins released by the decomposition of algae after death will also cause harm to aquatic organisms, and may even be transmitted through the food chain, posing a threat to human health.

[0004] In the soil environment, excessive accumulation of phosphates can also have a negative impact on soil ecology: on the one hand, excessive phosphates can change the chemical properties of the soil, affect the effectiveness of other nutrients in the soil, and thus affect plant growth; on the other hand, the accumulation of phosphates in the soil can also lead to soil acidification, reduce the buffering capacity of the soil, affect the activity of soil microorganisms, and destroy the balance of the soil ecosystem. In addition, phosphates in the soil may also enter the water body through surface runoff and leaching, further exacerbating the problem of eutrophication of water bodies. Therefore, the development of materials that can effectively adsorb phosphates to alleviate and improve the pollution problem of phosphates is of great significance to environmental protection.

[0005] Magnesium oxide is an adsorption material with high specific surface area, high adsorption performance and chemical stability. It has been widely used in the study of phosphate adsorption in recent years. The adsorption of phosphate by magnesium oxide is mainly achieved through chemical adsorption of phosphate by the hydroxyl groups on its surface. The hydroxyl groups on the surface of magnesium oxide can form hydrogen bonds and coordination bonds with phosphate ions, so that the phosphate ions are firmly adsorbed on the surface of magnesium oxide. Studies have shown that magnesium oxide has a large adsorption capacity for phosphate, a fast adsorption rate, and the adsorption process conforms to the quasi-second-order kinetic model, and has good adsorption performance.

[0006] However, due to the deficiencies in the preparation method and process, the existing rod-shaped magnesium oxide phosphate adsorbents have obvious defects in terms of adsorption capacity and adsorption rate, which seriously affects the application of rod-shaped magnesium oxide adsorbents in phosphate adsorption treatment. Therefore, developing a preparation method and process that can significantly improve the adsorption capacity and adsorption rate of rod-shaped magnesium oxide phosphate adsorbents is of great significance for the large-scale application of rod-shaped magnesium oxide phosphate adsorbents. Summary of the Invention

[0007] The object of the present invention is to overcome the problems of small adsorption capacity and slow adsorption rate existing in the existing rod-shaped magnesium oxide phosphate adsorbents, and to provide a rod-shaped phosphate adsorbent, its preparation method and application.

[0008] To achieve the above-mentioned invention object, the present invention provides a preparation method of a rod-shaped phosphate adsorbent, comprising the following steps: (1) Add a sodium carbonate solution with a concentration of 0.01 - 0.3 mol / L and a sodium hydroxide solution with a concentration of 0.01 - 0.1 mol / L to a magnesium nitrate solution with a concentration of 0.01 - 0.3 mol / L, and react for 3 - 5 h under the conditions of a stirring speed of 300 - 500 r / min and a temperature of 45 - 55 °C to obtain a suspension; wherein, the molar ratio of the magnesium nitrate, the sodium carbonate and the sodium hydroxide in the solution is controlled to be 1∶0.8 - 1.0∶0.4 - 0.2; (2) Perform solid-liquid separation treatment on the suspension to obtain a solid substance; (3) Perform drying treatment and pulverization treatment on the solid substance to obtain an adsorbent precursor; (4) Perform calcination treatment on the adsorbent precursor to obtain a rod-shaped phosphate adsorbent.

[0009] The preparation method of a rod-shaped phosphate adsorbent of the present invention, by specifically controlling the molar ratio of magnesium nitrate, sodium carbonate and sodium hydroxide during the reaction, makes the reaction product formed be a mixture of magnesium carbonate and magnesium hydroxide in a specific ratio. Thus, during calcination, by specifically adjusting the calcination process using the different decomposition temperatures of magnesium carbonate and magnesium hydroxide, the calcination process and the reaction product can have a synergistic effect, significantly improving the number, distribution and pore size of pores on the rod-shaped porous magnesium oxide, significantly increasing the specific surface area and oxygen vacancies of the obtained rod-shaped porous magnesium oxide, and thus significantly improving the adsorption capacity and efficiency for phosphates, and being more suitable for large-scale application as a phosphate adsorbent; this preparation method has simple steps, controllable process, and stable product performance, and is suitable for the large-scale production of rod-shaped phosphate adsorbents.

[0010] Among them, in step (1), preferably, the molar ratio of magnesium nitrate, sodium carbonate and sodium hydroxide in the solution is controlled to be 1∶0.9∶0.3; with the preferred molar ratio, the performance of the prepared phosphate adsorbent is better.

[0011] Among them, in step (2), preferably, the solid-liquid separation method is at least one of centrifugal separation method, filtration separation method, membrane separation method, and sedimentation separation method.

[0012] Among them, in step (3), preferably, the temperature of the drying treatment is 55-65°C and the time is 6-12h; through the drying treatment, the free water in the solid substance is removed, so as to avoid affecting the calcination effect due to the presence of free water during the later calcination process, and further affecting the performance of the adsorbent.

[0013] Preferably, the particle size of the adsorbent precursor is not greater than 50μm; with the preferred particle size, the particle size of the phosphate adsorbent obtained after calcination is smaller and the specific surface area is larger.

[0014] Among them, in step (4), preferably, the calcination adopts a segmented calcination process. The specific method is: first, the adsorbent precursor is heated from room temperature to 300-400°C at a heating rate of 1-3°C / min in an air atmosphere, and after holding for 1-2h, then heated to 500-600°C at a heating rate of 4-6°C, and held for 3-4h; the preferred calcination process can not only ensure that the adsorbent precursor is fully decomposed to form rod-shaped magnesium oxide, but also make the pore size and distribution formed on the structure of the rod-shaped magnesium oxide more uniform, the porosity higher, the specific surface area larger, and the adsorption amount and rate of phosphate significantly improved.

[0015] More preferably, the calcination method is: first, the adsorbent precursor is heated from room temperature to 350°C at a heating rate of 2°C / min in an air atmosphere, and after holding for 1.5h, then heated to 550°C at a heating rate of 5°C, and held for 3.5h.

[0016] In order to achieve the above-mentioned invention purpose, furthermore, the present invention also provides a rod-shaped phosphate adsorbent prepared by the above preparation method.

[0017] Preferably, the specific surface area of the phosphate adsorbent is not less than 60m 2 / g; with the preferred specific surface area, the adsorption efficiency of the phosphate adsorbent for phosphate is higher.

[0018] Preferably, the total pore volume of the phosphate adsorbent is not less than 0.20cm 3 / g; with the preferred total pore volume, the adsorption amount of the phosphate adsorbent for phosphate is higher.

[0019] Preferably, the average pore diameter of the phosphate adsorbent is 10-15 nm; with the preferred average pore diameter, the mechanical strength of the phosphate adsorbent is better, which is beneficial to avoiding the agglomeration and structural collapse of the phosphate adsorbent, and has a longer service life.

[0020] To achieve the above invention object, furthermore, the present invention also provides an application of a rod-shaped phosphate adsorbent, and the phosphate adsorbent is used for adsorbing and removing phosphate in an aqueous solution.

[0021] Preferably, the dosage of the phosphate adsorbent is 0.3-0.6 g / L; with the preferred dosage, the agglomeration of the phosphate adsorbent can be avoided, so that while having an excellent removal rate, the phosphate adsorbent has a better utilization rate.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The preparation method of the phosphate adsorbent of the present invention, by specifically controlling the molar ratio of magnesium nitrate, sodium carbonate and sodium hydroxide during the reaction, makes the resulting reaction product a mixture of magnesium carbonate and magnesium hydroxide in a specific ratio. Thus, during calcination, due to the different decomposition temperatures of magnesium carbonate and magnesium hydroxide, by specifically adjusting the calcination process, the calcination process and the reaction product can have a synergistic effect, significantly improving the quantity, distribution and pore size of the pores on the rod-shaped porous magnesium oxide, significantly increasing the specific surface area and oxygen vacancies of the obtained rod-shaped porous magnesium oxide, and thus significantly increasing the adsorption amount and efficiency of phosphate, and is also more suitable for large-scale application as a phosphate adsorbent.

[0023] 2. The preparation method of the phosphate adsorbent of the present invention has simple steps, a controllable process, and stable product performance, and is suitable for large-scale production of the rod-shaped phosphate adsorbent.

[0024] 3. The phosphate adsorbent of the present invention has the advantages of a large specific surface area and a high total pore volume, can achieve a high adsorption amount and high adsorption efficiency of phosphate, and is suitable for large-scale adsorption treatment of phosphate.

[0025] 4. The phosphate adsorbent of the present invention has excellent mechanical strength, which is beneficial to avoiding the agglomeration and structural collapse of the phosphate adsorbent, and has a longer service life.

[0026] 5. The phosphate adsorbent of the present invention is used for adsorbing and removing phosphate in an aqueous solution, and by limiting its dosage, the utilization rate of the phosphate adsorbent can be effectively improved. Specific Embodiments

[0027] To more clearly describe the invention purpose, technical solution, and technical effect advantages in the specific embodiments of the present invention, the following will provide a detailed description in combination with the solutions in the specific embodiments of the present invention. The specific technical solutions involved in the following specific embodiments are only for clearly and completely describing the innovative technical solutions of the present invention. They are only a part of the specific implementation solutions that the present invention can adopt, not all the embodiments, and should not be understood as a limitation to the innovative solutions of the present invention. Any solution adopting the same inventive concept of the present invention should be included in the protection scope of the present invention.

[0028] For those skilled in the art, when understanding the solutions described in the specific embodiments of the present invention, they can refer to the conventional technical manuals in the art. At the same time, for the places where the above terms appear, they can make appropriate understandings or adjustments referentially. Without creative labor, the same or similar technical solution implementation situations can be deduced.

[0029] Example 1 A rod-shaped phosphate adsorbent is prepared by the following preparation method: (1) Add a sodium carbonate solution with a concentration of 0.2 mol / L and a sodium hydroxide solution with a concentration of 0.2 mol / L to a magnesium nitrate solution with a concentration of 0.2 mol / L. React for 4 h under the conditions of a stirring speed of 400 r / min and a temperature of 50 °C to obtain a suspension; among them, control the molar ratio of magnesium nitrate, sodium carbonate, and sodium hydroxide in the solution to be 1∶0.9∶0.3; (2) Filter the suspension to obtain a solid substance; (3) Dry the solid substance (temperature is 60 °C, time is 10 h) and crush it (particle size is not greater than 50 μm) to obtain an adsorbent precursor; (4) Calcinate the adsorbent precursor (first heat the adsorbent precursor in an air atmosphere at a heating rate of 2 °C / min to 350 °C, keep it calcined for 1.5 h, and then heat it at a heating rate of 5 °C to 550 °C, keep it calcined for 3.5 h) to obtain a rod-shaped phosphate adsorbent.

[0030] Example 2 A rod-shaped phosphate adsorbent is prepared by the following preparation method: (1) Add a sodium carbonate solution with a concentration of 0.3 mol / L and a sodium hydroxide solution with a concentration of 0.3 mol / L to a magnesium nitrate solution with a concentration of 0.3 mol / L. React for 3 h under the conditions of a stirring speed of 500 r / min and a temperature of 55 °C to obtain a suspension; among them, control the molar ratio of magnesium nitrate, sodium carbonate, and sodium hydroxide in the solution to be 1∶0.8∶0.4; (2) Filter the suspension to obtain solid matter; (3) Dry the solid matter (at a temperature of 65 °C for 6 h) and crush it (with a particle size not greater than 40 μm) to obtain the adsorbent precursor; (4) Calcinate the adsorbent precursor (first heat the adsorbent precursor in an air atmosphere at a heating rate of 3 °C / min to 400 °C, hold for 1 h, and then heat it at a heating rate of 6 °C to 600 °C and hold for 4 h) to obtain a phosphate adsorbent with a rod-like structure.

[0031] Example 3 A phosphate adsorbent with a rod-like structure is prepared by the following preparation method: (1) Add a sodium carbonate solution with a concentration of 0.01 mol / L and a sodium hydroxide solution with a concentration of 0.1 mol / L to a magnesium nitrate solution with a concentration of 0.01 mol / L, and react at a stirring speed of 300 r / min and a temperature of 45 °C for 5 h to obtain a suspension; wherein, the molar ratio of magnesium nitrate, sodium carbonate, and sodium hydroxide in the solution is controlled to be 1∶1.0∶0.2; (2) Filter the suspension to obtain solid matter; (3) Dry the solid matter (at a temperature of 55 °C for 12 h) and crush it (with a particle size not greater than 50 μm) to obtain the adsorbent precursor; (4) Calcinate the adsorbent precursor (first heat the adsorbent precursor in an air atmosphere at a heating rate of 1 °C / min to 300 °C, hold for 2 h, and then heat it at a heating rate of 4 °C to 500 °C and hold for 4 h) to obtain a phosphate adsorbent with a rod-like structure.

[0032] Comparative Example 1 A phosphate adsorbent with a rod-like structure is prepared by the following preparation method: (1) Add a sodium carbonate solution with a concentration of 0.2 mol / L to a magnesium nitrate solution with a concentration of 0.2 mol / L, and react at a stirring speed of 400 r / min and a temperature of 50 °C for 4 h to obtain a suspension; wherein, the molar ratio of magnesium nitrate, sodium carbonate, and sodium hydroxide in the solution is controlled to be 1∶1.2; (2) Filter the suspension to obtain solid matter; (3) Dry the solid matter (at a temperature of 60 °C for 10 h) and crush it (with a particle size not greater than 50 μm) to obtain the adsorbent precursor; (4) Calcinate the adsorbent precursor (first, heat the adsorbent precursor in an air atmosphere at a heating rate of 2 °C / min to 350 °C, keep it calcined for 1.5 h, then heat it at a heating rate of 5 °C to 550 °C, and keep it calcined for 3.5 h) to obtain a phosphate adsorbent with a rod-like structure.

[0033] Comparative Example 2 A phosphate adsorbent with a rod-like structure is prepared by the following preparation method: (1) Add a sodium carbonate solution with a concentration of 0.2 mol / L and a sodium hydroxide solution with a concentration of 0.2 mol / L to a magnesium nitrate solution with a concentration of 0.2 mol / L, and react at a stirring speed of 400 r / min and a temperature of 50 °C for 4 h to obtain a suspension; wherein, the molar ratio of the magnesium nitrate, the sodium carbonate, and the sodium hydroxide in the solution is controlled to be 1:0.7:0.5; (2) Filter the suspension to obtain a solid substance; (3) Dry the solid substance (at a temperature of 60 °C for 10 h) and crush it (with a particle size not greater than 50 μm) to obtain an adsorbent precursor; (4) Calcinate the adsorbent precursor (first, heat the adsorbent precursor in an air atmosphere at a heating rate of 2 °C / min to 350 °C, keep it calcined for 1.5 h, then heat it at a heating rate of 5 °C to 550 °C, and keep it calcined for 3.5 h) to obtain a phosphate adsorbent with a rod-like structure.

[0034] Comparative Example 3 A phosphate adsorbent with a rod-like structure is prepared by the following preparation method: (1) Add a sodium carbonate solution with a concentration of 0.2 mol / L and a sodium hydroxide solution with a concentration of 0.2 mol / L to a magnesium nitrate solution with a concentration of 0.2 mol / L, and react at a stirring speed of 400 r / min and a temperature of 50 °C for 4 h to obtain a suspension; wherein, the molar ratio of the magnesium nitrate, the sodium carbonate, and the sodium hydroxide in the solution is controlled to be 1:1.1:0.1; (2) Filter the suspension to obtain a solid substance; (3) Dry the solid substance (at a temperature of 60 °C for 10 h) and crush it (with a particle size not greater than 50 μm) to obtain an adsorbent precursor; (4) Calcinate the adsorbent precursor (first, heat the adsorbent precursor in an air atmosphere at a heating rate of 2 °C / min to 350 °C, keep it calcined for 1.5 h, then heat it at a heating rate of 5 °C to 550 °C, and keep it calcined for 3.5 h) to obtain a phosphate adsorbent with a rod-like structure.

[0035] Comparative Example 4 A phosphate adsorbent with a rod-like structure was prepared by the following preparation method: (1) A sodium carbonate solution with a concentration of 0.2 mol / L and a sodium hydroxide solution with a concentration of 0.2 mol / L were added to a magnesium nitrate solution with a concentration of 0.2 mol / L. Under the conditions of a stirring speed of 400 r / min and a temperature of 50 °C, the reaction was carried out for 4 h to obtain a suspension; wherein, the molar ratio of the magnesium nitrate, the sodium carbonate, and the sodium hydroxide in the solution was controlled to be 1:0.9:0.3; (2) The suspension was filtered to obtain a solid substance; (3) The solid substance was dried (at a temperature of 60 °C for 10 h) and pulverized (with a particle size not greater than 50 μm) to obtain a precursor of the adsorbent; (4) The precursor of the adsorbent was calcined (the precursor of the adsorbent was heated to 550 °C at a heating rate of 2 °C / min in an air atmosphere and calcined for 5 h) to obtain a phosphate adsorbent with a rod-like structure.

[0036] Comparative Example 5 A phosphate adsorbent with a rod-like structure was prepared by the following preparation method: (1) A sodium carbonate solution with a concentration of 0.2 mol / L and a sodium hydroxide solution with a concentration of 0.2 mol / L were added to a magnesium nitrate solution with a concentration of 0.2 mol / L. Under the conditions of a stirring speed of 400 r / min and a temperature of 50 °C, the reaction was carried out for 4 h to obtain a suspension; wherein, the molar ratio of the magnesium nitrate, the sodium carbonate, and the sodium hydroxide in the solution was controlled to be 1:0.9:0.3; (2) The suspension was filtered to obtain a solid substance; (3) The solid substance was dried (at a temperature of 60 °C for 10 h) and pulverized (with a particle size not greater than 50 μm) to obtain a precursor of the adsorbent; (4) The precursor of the adsorbent was calcined (the precursor of the adsorbent was heated to 550 °C at a heating rate of 5 °C / min in an air atmosphere and calcined for 5 h) to obtain a phosphate adsorbent with a rod-like structure.

[0037] Comparative Example 6 A phosphate adsorbent with a rod-like structure was prepared by the following preparation method: (1) Add a sodium carbonate solution with a concentration of 0.2 mol / L and a sodium hydroxide solution with a concentration of 0.2 mol / L to a magnesium nitrate solution with a concentration of 0.2 mol / L. React for 4 h at a stirring speed of 400 r / min and a temperature of 50 °C to obtain a suspension; wherein, control the molar ratio of the magnesium nitrate, the sodium carbonate, and the sodium hydroxide in the solution to be 1∶0.9∶0.3; (2) Filter the suspension to obtain a solid substance; (3) Dry the solid substance (at a temperature of 60 °C for 10 h) and crush it (the particle size is not more than 50 μm) to obtain a precursor of the adsorbent; (4) Calcinate the precursor of the adsorbent (first heat the precursor of the adsorbent in an air atmosphere at a heating rate of 5 °C / min to 350 °C, keep it calcined for 1.5 h, and then heat it to 550 °C at a heating rate of 2 °C and keep it calcined for 3.5 h) to obtain a rod-shaped phosphate adsorbent.

[0038] Experimental Example 1: Conduct experimental tests on the specific surface area, total pore volume, average pore diameter, and pore size distribution of the phosphate adsorbents prepared in Examples 1-3 and Comparative Examples 1-6, and record the relevant test results as shown in the following table:

[0040] Experimental Example 2: Conduct determination experiments on the phosphate equilibrium adsorption capacity, phosphorus removal efficiency, and reaction rate constant of the phosphate adsorbents prepared in Examples 1-3 and Comparative Examples 1-6 for the solution to be treated (a sodium phosphate solution with a concentration of 0.05 mol / L and a pH value of 4.5) (the dosage is: 0.5 g / L), and the results are as follows:

[0042] Experimental Example 3: Conduct an experiment on the effect of the dosage of the phosphate adsorbent on the phosphorus removal efficiency of the solution to be treated (a sodium phosphate solution with a concentration of 0.05 mol / L and a pH value of 4.5) using the phosphate adsorbent prepared in Example 1, and the results are as follows:

[0043] ; Analyzing the data of Experimental Example 1, Experimental Example 2, and Experimental Example 3 above, it can be seen that by specifically controlling the molar ratios of magnesium nitrate, sodium carbonate, and sodium hydroxide during the reaction process, the present invention enables the reaction product to be a mixture of magnesium carbonate and magnesium hydroxide in a specific ratio. Thus, during calcination, by specifically adjusting the calcination process taking advantage of the different decomposition temperatures of magnesium carbonate and magnesium hydroxide, the calcination process and the reaction product can have a synergistic effect, significantly improving the number, distribution, and pore size of the pores on the rod-shaped porous magnesium oxide, and significantly increasing both the adsorption amount and efficiency of the obtained rod-shaped porous magnesium oxide for phosphates. At the same time, when the dosage of the phosphate adsorbent of the present invention is 0.3 - 0.6 g / L, the removal rate of phosphates is significantly increased.

Claims

1. A method for preparing a phosphate adsorbent in a rod-like structure, characterized in that, It includes the following steps: (1) Add a sodium carbonate solution with a concentration of 0.01 - 0.3 mol / L and a sodium hydroxide solution with a concentration of 0.01 - 0.1 mol / L to a magnesium nitrate solution with a concentration of 0.01 - 0.3 mol / L. Under the conditions of a stirring speed of 300 - 500 r / min and a temperature of 45 - 55 °C, react for 3 - 5 h to obtain a suspension; wherein, the molar ratio of the magnesium nitrate, the sodium carbonate, and the sodium hydroxide in the solution is controlled to be 1∶0.8 - 1.0∶0.4 - 0.2; (2) Perform solid-liquid separation on the suspension to obtain a solid substance; (3) Perform drying treatment and crushing treatment on the solid substance to obtain an adsorbent precursor; (4) Perform calcination treatment on the adsorbent precursor to obtain a rod-shaped phosphate adsorbent; Among them, the calcination adopts a segmented calcination process. The specific method is: first heat the adsorbent precursor in an air atmosphere at a heating rate of 1 - 3 °C / min to 300 - 400 °C, keep it calcined for 1 - 2 h, and then heat it at a heating rate of 4 - 6 °C to 500 - 600 °C, and keep it calcined for 3 - 4 h.

2. The preparation method of the phosphate adsorbent according to claim 1, wherein In step (2), the solid-liquid separation method is at least one of centrifugal separation method, filtration separation method, membrane separation method, and sedimentation separation method.

3. The preparation method of the phosphate adsorbent according to claim 1, characterized in that, In step (3), the drying temperature is 55 - 65 °C and the time is 6 - 12 h.

4. The preparation method of the phosphate adsorbent according to claim 1, wherein, In step (3), the particle size of the adsorbent precursor is not greater than 50 μm.

5. A phosphate adsorbent prepared by the preparation method according to any one of claims 1 - 4.

6. The phosphate adsorbent according to claim 5, wherein The specific surface area of the phosphate adsorbent is not less than 60 m2 / g.

7. The phosphate adsorbent according to claim 5, wherein The total pore volume of the phosphate adsorbent is not less than 0.20 cm3 / g.

8. The phosphate adsorbent according to claim 5, characterized in that, The average pore diameter of the phosphate adsorbent is 10 - 15 nm.

9. Use of the phosphate adsorbent according to any one of claims 5-8, characterized in that, The phosphate adsorbent is used for adsorbing and removing phosphate in an aqueous solution.

10. Use of the phosphate adsorbent according to claim 9, characterized in that, The dosage of the phosphate adsorbent is 0.3 - 0.6 g / L.

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